/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.mpp.execution.schedule.task;

import com.google.common.util.concurrent.ListenableFuture;
import io.airlift.units.Duration;
import org.apache.iotdb.db.mpp.common.FragmentInstanceId;
import org.apache.iotdb.db.mpp.common.PlanFragmentId;
import org.apache.iotdb.db.mpp.common.QueryId;
import org.apache.iotdb.db.mpp.execution.driver.IDriver;
import org.apache.iotdb.db.mpp.execution.exchange.ISinkHandle;
import org.apache.iotdb.db.mpp.execution.schedule.DriverTaskThread;
import org.apache.iotdb.db.mpp.execution.schedule.ExecutionContext;
import org.apache.iotdb.db.mpp.execution.schedule.queue.ID;
import org.apache.iotdb.db.mpp.execution.schedule.queue.IDIndexedAccessible;

import java.util.Comparator;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * the scheduling element of {@link DriverTaskThread}. It wraps a single Driver.
 */
public class DriverTask implements IDIndexedAccessible {

    private DriverTaskID id;
    private DriverTaskStatus status;
    private final IDriver fragmentInstance;

    // the higher this field is, the higher probability it will be scheduled.
    private volatile double schedulePriority;
    private final long ddl;
    private final Lock lock;

    // Running stats
    private long cpuWallNano;

    private String abortCause;

    private long lastEnterReadyQueueTime;
    private long lastEnterBlockQueueTime;

    /**
     * Initialize a dummy instance for queryHolder
     */
    public DriverTask() {
        this(new StubFragmentInstance(), 0L, null);
    }

    public DriverTask(IDriver instance, long timeoutMs, DriverTaskStatus status) {
        this.fragmentInstance = instance;
        this.id = new DriverTaskID(instance.getInfo());
        this.setStatus(status);
        this.schedulePriority = 0.0D;
        this.ddl = System.currentTimeMillis() + timeoutMs;
        this.lock = new ReentrantLock();
    }

    public DriverTaskID getId() {
        return id;
    }

    @Override
    public void setId(ID id) {
        this.id = (DriverTaskID) id;
    }

    public DriverTaskStatus getStatus() {
        return status;
    }

    public boolean isEndState() {
        return status == DriverTaskStatus.ABORTED || status == DriverTaskStatus.FINISHED;
    }

    public IDriver getFragmentInstance() {
        return fragmentInstance;
    }

    public void setStatus(DriverTaskStatus status) {
        this.status = status;
    }

    /**
     * Update the schedule priority according to the execution context.
     *
     * @param context the last execution context.
     */
    public void updateSchedulePriority(ExecutionContext context) {
        // TODO: need to implement more complex here

        // 1. The penalty factor means that if a task executes less time in one schedule, it will have a
        // high schedule priority
        double penaltyFactor =
                context.getCpuDuration().getWall().getValue(TimeUnit.NANOSECONDS)
                        / context.getTimeSlice().getValue(TimeUnit.NANOSECONDS);
        // 2. If a task is nearly timeout, it should be scheduled as soon as possible.
        long base = System.currentTimeMillis() - ddl;

        // 3. Now the final schedulePriority is out, this may not be so reasonable.
        this.schedulePriority = base * penaltyFactor;
    }

    public void lock() {
        lock.lock();
    }

    public void unlock() {
        lock.unlock();
    }

    public double getSchedulePriority() {
        return schedulePriority;
    }

    public long getDDL() {
        return ddl;
    }

    @Override
    public int hashCode() {
        return id.hashCode();
    }

    @Override
    public boolean equals(Object o) {
        return o instanceof DriverTask && ((DriverTask) o).getId().equals(id);
    }

    public String getAbortCause() {
        return abortCause;
    }

    public void setAbortCause(String abortCause) {
        this.abortCause = abortCause;
    }

    public long getLastEnterReadyQueueTime() {
        return lastEnterReadyQueueTime;
    }

    public void setLastEnterReadyQueueTime(long lastEnterReadyQueueTime) {
        this.lastEnterReadyQueueTime = lastEnterReadyQueueTime;
    }

    public long getLastEnterBlockQueueTime() {
        return lastEnterBlockQueueTime;
    }

    public void setLastEnterBlockQueueTime(long lastEnterBlockQueueTime) {
        this.lastEnterBlockQueueTime = lastEnterBlockQueueTime;
    }

    /**
     * a comparator of ddl, the less the ddl is, the low order it has.
     */
    public static class TimeoutComparator implements Comparator<DriverTask> {

        @Override
        public int compare(DriverTask o1, DriverTask o2) {
            if (o1.getId().equals(o2.getId())) {
                return 0;
            }
            if (o1.getDDL() < o2.getDDL()) {
                return -1;
            }
            if (o1.getDDL() > o2.getDDL()) {
                return 1;
            }
            return o1.getId().compareTo(o2.getId());
        }
    }

    /**
     * a comparator of ddl, the higher the schedulePriority is, the low order it has.
     */
    public static class SchedulePriorityComparator implements Comparator<DriverTask> {

        @Override
        public int compare(DriverTask o1, DriverTask o2) {
            if (o1.getId().equals(o2.getId())) {
                return 0;
            }
            if (o1.getSchedulePriority() > o2.getSchedulePriority()) {
                return -1;
            }
            if (o1.getSchedulePriority() < o2.getSchedulePriority()) {
                return 1;
            }
            return o1.getId().compareTo(o2.getId());
        }
    }

    private static class StubFragmentInstance implements IDriver {

        private static final QueryId stubQueryId = new QueryId("stub_query");
        private static final FragmentInstanceId stubInstance =
                new FragmentInstanceId(new PlanFragmentId(stubQueryId, 0), "stub-instance");

        @Override
        public boolean isFinished() {
            return false;
        }

        @Override
        public ListenableFuture<?> processFor(Duration duration) {
            return null;
        }

        @Override
        public FragmentInstanceId getInfo() {
            return stubInstance;
        }

        @Override
        public void close() {
        }

        @Override
        public void failed(Throwable t) {
        }

        @Override
        public ISinkHandle getSinkHandle() {
            return null;
        }
    }
}
